1. Field of the Invention
The present invention relates to equipment for the sport of golf. The invention concerns, more particularly, a golf club having a shaft that encloses a damping element, such as a fluid-filled chamber or a polymer foam member, for example.
2. Description of Background Art
The formal origins of the game of golf, one of the oldest international sports, dates to the 16th century at The Royal and Ancient Golf Club at St. Andrews, located in Scotland. During successive centuries, the game of golf has gained and maintained a populous following due to inherent challenges of the game, a respected reputation, and its suitability for relaxation. Due to an increasing growth in the number of individuals playing the game of golf, manufacturers of golf equipment, which includes golf clubs, balls, and footwear, regularly modify and improve upon the various features and characteristics of the golf equipment. Golf equipment has, therefore, evolved over time to provide enhanced performance and suitability for a wide range of playing abilities and styles, with many of the advances relating to the configuration and materials that are utilized in the golf equipment.
Advancements in golf technology also apply to golf clubs, which are utilized to propel a golf ball toward an intended target. The primary elements of a golf club are a head that is secured to an end of a shaft. Although some traditional golf club heads were formed from wood or combinations of wood and steel, a modern head is primarily formed from one or more metals, such as steel, aluminum, or titanium. Similarly, traditional golf club shafts were often fashioned from wood, whereas a modern shaft is commonly formed from either metal or graphite materials.
During the game of golf, an individual grasps the shaft and swings the golf club such that the head traverses a generally arcuate path and impacts a golf ball. A portion of the inertia of the golf club, and particularly the inertia of the head, is then transferred to the golf ball and propels the golf ball toward the intended target. One factor that influences the trajectory of the golf ball following impact is the configuration of the shaft and materials that are utilized in the shaft. Although a golf club shaft may have a hollow, cylindrical configuration with a constant thickness throughout the length of the shaft, many modern shafts exhibit a tapered or stepped configuration. That is, the diameter of the shaft decreases from the area where the individual grasps the shaft to the area where the head is secured to the shaft. The configuration of the shaft and the material selected for the shaft have an effect upon the performance characteristics of the shaft, which include the degree of flex in the shaft, the position of the kick point, and the torque necessary to twist the shaft, for example.
Depending upon the specific shaft configuration, vibrations may arise in the shaft following impact with the golf ball or the ground. Although absorbing a portion of the vibrational forces does not generally pose concerns, repeatedly absorbing a portion of the vibrational forces may affect the hands or the joints of the individual. In general, the configuration of the shaft (e.g., thickness, material, degree of tapering, etc.) may be modified to lessen the amplitude or adjust the frequency of the shaft, but such modifications may have an adverse effect upon the performance characteristics of the shaft.